1. Technical Field
The present invention relates to keyboard devices in general, and particularly to a keyboard device used in an electronic apparatus.
2. Description of Related Art
A keyboard device used in an electronic apparatus such as a laptop personal computer (laptop PC) is normally equipped with a base plate, a membrane sheet provided on the upper or lower surface of the base plate, and a key top vertically movably arranged on the upper surface side of the base plate by a pantograph. In such a keyboard device, the corresponding signal is output to a key depressed by making contacting/separating action of the contact of the membrane sheet when the key top is depressed. When the depression of the key top is released, the key top is reset to its original position by the elastic force of a rubber dome (elastic member) provided inside.
The keyboard device generates a suitable repulsive force (or biasing force) when a user depresses the key top with a configuration based on the pantograph and the rubber dome and realizes high usability. To make a thinner keyboard device is relatively difficult because of the usage of rubber domes. For one prior art thin keyboard design, an actuator is placed thereinside and a haptic feedback (or vibration) is provided when a key is depressed. One problem with this thin keyboard design is that vibration is different in touch from the “click” of a key, and the usability is degraded with no suitable repulsive force. Consequently, it would be desirable to provide an improved thin keyboard design.